1. Field of the Invention
The present invention relates to an image processing method and apparatus and, more particularly, to an image processing apparatus and method which interpolates images obtained by a plurality of image sensing means (e.g., cameras) to generate an image viewed from a viewpoint different from the viewpoints of the image sensing means.
2. Description of the Related Art
As an apparatus for stereoscopically displaying images viewed from a plurality of viewpoints, a stereo display, a lenticular display, and the like are available. The above stereo display is designed to alternately display images obtained by two cameras upon high-speed switching. An observer can observe a stereoscopic image by using shutter glasses or polarization glasses which are synchronized with this high-speed switching operation.
In the lenticular display, for example, images A, B, C, and D obtained by four cameras are arranged in units of pixels, as shown in FIG. 1, provided that the pixel position (1,1) of the first image A is expressed as A (1,1). A sheet called a lenticular sheet obtained by arranging a large number of semicylindrical lenses is bonded to a front surface to allow stereoscopic expression of images viewed from four viewpoints.
In the above conventional apparatus, however, only stereoscopic images in the directions in which the cameras are aimed can be observed. That is, in the stereo display, when an object is photographed while the two cameras are fixed, the observer always sees the same image even if the observer moves his/her viewpoint.
In contrast to this, in the lenticular display, the observer can move his/her viewpoint in the lateral direction. However, the observer can only see images viewed from some of the cameras at intervals. That is, the viewpoint of the observer cannot be continuously moved in the lateral direction or in a space (i.e., the viewpoint cannot be moved to an arbitrary position in a space to aim the viewpoint in an arbitrary direction).
A method of using an epipolar plane image (to be referred to as an EPI hereinafter) is a conventional method of using a plurality of images photographed from a plurality of viewpoint positions to generate images viewed from positions different from the respective photographing positions.
In this method, as shown in FIG. 2, lines (101a, 102a, 103a, 104a) in the respective images (101, 102, 103, 104) at the same position are extracted and synthesized into one image (2000). Straight line detection is then performed on this EPI, and interpolation processing is performed to obtain interpolated lines (101axe2x80x2, 102axe2x80x2, 103axe2x80x2), thereby obtaining points (corresponding points) corresponding to target points. From each corresponding point, an image viewed from a position different from a photographing position is obtained.
In the above conventional apparatus, a sequence of points forming a straight line on an EPI as discrete data is regarded as corresponding points. For this reason, if, for example, straight lines of the same color appear at equal intervals on an EPI to form a stripped pattern, or thin lines are present in an uniform area, a sequence of points which is not regarded as corresponding points may be mistakenly detected as a straight line. An image therefore is constructed on the basis of information including the erroneous corresponding points, resulting in synthesizing a distorted image, e.g., an image whose forward/backward positional relationship is reversed, or an image having a distorted pattern.
The present invention has been made in consideration of the above problem, and has as its object to allow smooth movement of the viewpoint position and its view direction of an observer in a space and generate corresponding images.
It is another object of the present invention to provide an image processing apparatus and method which can accurately generate interpolated images in the image interpolation processing required to achieve the above object.
The foregoing object is attained by providing an image processing method comprising: multi-viewpoint image input step for inputting images obtained from a plurality of viewpoint positions arranged on different straight lines; detection step for detecting a viewpoint position and its view direction; and image generation step for generating a virtual image viewed from the predetermined viewpoint by using the images input in the multi-viewpoint image input step on the basis of the detected predetermined viewpoint position and the direction in which the user is seeing at the predetermined viewpoint.
The foregoing object is also attained by providing an image processing method comprising: array detection step for detecting a plurality of arrays of straight lines having widths on an epipolar plane image constituted by a plurality of images photographed from a plurality of viewpoint positions; and corresponding point determination step for determining corresponding points by selecting a wider array from the plurality of arrays.
The foregoing object is also attained by providing an image processing apparatus comprising: multi-viewpoint image input means for inputting images obtained from a plurality of viewpoint positions arranged on different straight lines; detection means for detecting a viewpoint position and its view direction; and image generation means for generating a virtual image viewed from the predetermined viewpoint by using the images input in the multi-viewpoint image input means on the basis of the detected predetermined viewpoint position and the direction in which the user is seeing at the predetermined viewpoint.
The foregoing object is also attained by providing an image processing apparatus comprising: array detection means for detecting a plurality of arrays of straight lines having widths on an epipolar plane image constituted by a plurality of images photographed from a plurality of viewpoint positions; and corresponding point determination means for determining corresponding points by selecting a wider array from the plurality of arrays.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.